It looks like pretty odd behaviour, but as Torres explains, there's a very good reason behind it: sodium. As Torres explains:

There's no sodium readily available for butterflies in their normal diet of leaves as caterpillars, or nectar as adults. So where do they get it? Yes -- salty turtle tears.

Torres' footage shows about eight species of butterflies swarming around what appears to be yellow-spotted sideneck turtles (Podocnemis unifilis), a type of turtle that comes out of the water to sun itself and is unable to retract its head back into its shell -- something that makes it more convenient for insects to drink up those salty tears. As Torres explains on Live Science, it's an example of commensalism, a partnership between species where one benefits and the other doesn't get affected neither positively or negatively.

In addition to these bodily fluids, butterflies apparently also get their required sodium intake from drinking water from muddy, almost-dried out river beds, and (yuck) jaguar poop -- probably the grossest thing we've heard about butterflies thus far. But these otherwise beautiful insects imbibing the salty drops from a turtle's eye are yet another example of what a wild and surprising world is out there; see more over at Phil Torres, on YouTube, Twitter and Instagram.